Lab 8

(A) Objectives: 1. To verify Kirchhoff’s Voltage Law in RLC series circuit. 2. To verify Kirchhoff’s Current Law in RLC parallel circuit.

(B) Equipments and Components: 1. Resistor : 1kΩ , 10Ω 2. Capacitor : 0.01µF 3. Inductor : 10mH 4. Breadboard 5. Signal Generator 6. Multimeter

7. Oscilloscope

(C) Procedures: A. To verify Kirchhoff’s Voltage Law in RLC series circuit.

Figure 1

1. Circuit as diagram on breadboard was assembled. 2. R was measured using a multimeter. 3. Voltage of every components (VR, VL and Vc) with E=8 Vp-p was measured using an

oscilloscope. 4. Ip-p was calculated using the equation Ip-p = V

Rp-p

/ Rmeasured

5. ZT was calculated using equation ZT = Ep-p / Ip-p 6. Using L and C values used and Rmeasured, ZT was calculated and the result was

compared with the result in step 4. 7. I, VR, VL and VC were calculated using peak-to-peak values and E=8V

0°.

8. Phasor diagram was drawn including I and all voltages. 9. Kirchhoff’s Law was vrified by showing E =

(VR 2 + (VL – VC)2) using peak-to-peak

voltage values. 10. Voltage divider method was used to calculate Vab(p-p) 11. The observation from the experiment were discussed.

B. To verify Kirchhoff’s Current Law in RLC parallel circuit.

1. Circuit was assemble as diagram on breadboard 2. current was measured through of every components (IR1, IL and Ic) with E=8 Vp-p using

the multimeter. 3. Verify the Kirchhoff’s Law by calculating IS using the equation IS = IR1 + IL + IC

4. Discuss the observation from the experiment.

Result : Series Circuit 1. Rmeasured = 980 Ω

2. Components R1 (VRp-p) L1 (VLp-p) C1 (Vcp-p)

Voltage 8V 8V 0.8 V

Voltage measure using oscilloscope.

3. Calculate Ip-p using this equation;

Ip-p

= VRp-p / Rmeasured = 8 V / 980 Ω = 8.163 mA

4. Calculate the ZT

ZT

= Ep-p / Ip-p = 8 V / 8.163 mA

= 980 Ω

5. Using L and C values used and Rmeasured, calculate ZT .

ω

= 2πf = 2π(1000Hz) = 6283.19

Xc

= 1/ωc

= 1 / 6283.19 (0.01 x 10-6) = 15915.48Ω

Zc

= 1 / jωc

= 15915.48Ω

XL

= ωL = 6283.19 (10 x 10-3) = 62.8319Ω

ZL

= jωL = 62.8319 ∠ - 90°

ZT

= R + j XL - j Xc = 1000 + j62.8319 - j15915.48 = 1000Ω

= 15915.48 ∠ - 90°

6. Using E = 8 V ∠ 0° , calculate I, VR, VL and VC using peak-to-peak values.

I

= V / ZT = 8 ∠ - 0° / 15884.16 ∠ - 86.39° = 5.0366 x 10-4∠ 86.39°A

V

= IR = 5.0366 x 10-4∠ 86.39° x 1000 ∠ 0° = 0.50366 ∠ 86.39°V

VL

= Ij XL = 5.0366 x 10-4 (j62.8319) = 0.03165 ∠ 90°V

VC

= Ij XC = 5.0366 x 10-4 (-j 15915.48) = 8.01599 ∠ -90°V

7. Draw phasor diagram including I and all voltages.

8. E

= √(VR2 + (VL - VC)2) = √(82 + (8 - 8)2) = 8V

9. Vab(p-p) = E ∠ 0° x (ZLC / ZT) ∠ 0°

ZLC

= ZL + ZC

= j ZL – j ZC = (62.8319 ∠ 90°) + (15915.48 ∠ -90°) = 15852.96 ∠ -90°

Vab(p-p) = (8 ∠ 0°) x (15852.96 ∠ -90°) / 15884.16 ∠ - 86.39° = 7.9841 ∠ -90°

10. Vab

= 8V

Parallel Circuit 1. Components IR1 IL IC

Current 8.00 mA 128.00 mA 5.00 mA

IS = IR1 + IL + IC = 8.00 mA + 128.00 mA + 5.00 mA = 141 mA

2. Verify Kirchhoff’s Law by calculation IR

= 8 ∠ 0° / 970Ω

= 8.247 x 10-3 ∠ 0°

IL = 8 ∠ 0° / 62.8319 ∠ 90°

= 0.12732 ∠ -90°

IC = 8 ∠ 0° / 15915.48 ∠ -90° = 5.0266 ∠ 90° IS

= IR + IL + IC

= 0.12707 ∠ 86.39°

Discussion: 1. RLC circuit contains resistance, inductance, and capacitance. 2. Inductive reactance and capacitive reactance have opposite effect on the circuit phase

angle. 3. Each of the three ideal circuit elements may be represented by one such impedance element

Suggestions for further work in the future: 1. Prepare the electrical and electronic components which in good condition. 2. Do not use red maker while writing on the whiteboard because it is unclear.

3. Use LCD projector to show how to do the experiment. 4. Use microphone to give the explanation.

Conclusions: 1. Kirchhoff’s Voltage Law in RLC series circuit is verified 2. Kirchhoff’s Current Law in RLC parallel circuit is verified

References: 1. J. David Irwin, Basic Engineering Circuit Analysis, (7th Edition), John Wiley and Sons

Inc,2002 2. David E. Johnson, John L. Hilburn, Johnny R. Johnson, Peter D. Scott, Basic Electric

Circuit Analysis, (5th Edition), Prentice Hall, 1995 3. Robert J. Herrick, DC/AC Circuits and Electronics: Principles & Applications, Theorem Delwan Learning, New York, 2003 4. Thomas L. Floyd, Principles Of Electric Circuits: Electron Flow Version, (3rd Edition),

Macmillan Publishing Company, New York, 1993 5. Thomas L. Floyd, Principles Of Electric Circuits: Conventional Current Versions, (8th

Edition), Pearson Prentice Hall, New Jersey, 2007